The present invention relates to a jig for mounting metal balls, particularly metal balJs smaller than 1 mm, to a semiconductor chip substrate or a circuit board for soldering.
It has been customary to mount metal balls to electrode pads arranged on a substrate and connect an LSI (Large Scale Integrated circuit) or similar semiconductor to the substrate via the metal balls. The metal balls are as small as about 0.6 mm in BGAs (Ball Grid Arrays) currently predominant in the semiconductors art or as small as 0.3 mm to 0.4 mm in CSPs (Chip Size Packages) recently put to practical use. Future metal balls for such applications are expected to have diameters even smaller than 0.15 mm.
Metal balls to be mounted to the electrode pads of a substrate are usually implemented by solder balls. Japanese Patent Laid-Open Publication No. 5-299424, for example, discloses a method of mounting solder balls to electrode pads formed on a semiconductor substrate. However, the method taught in this document has a problem that a guide plate, or transfer mask, formed with holes for receiving metal balls cannot be reduced in thickness. Further, when the dimensional accuracy of the contour of a container storing metal balls and the contour of a suction head is low, the balls cannot be accurately mounted to the electrode pads. In addition, the guide plate is not replaceable.
Technologies relating to the present invention are also disclosed in, e.g., Japanese Patent Laid-Open Publication No. 8-167611.